Abstract:
Safflower (Carthamus
tinctorius) is a highly branched, herbaceous,
thistle-like annual plant. It is commercially
cultivated for vegetable oil extracted from
the seeds, which is cultivated under arid
environments. In such environments, the
water needed for germination is available
for only a short time and, consequently,
successful crop establishment depends not
only on rapid and uniform germination of
the seedlot, but also on its ability to
germinate under low water availability. All
of these attributes can be analyzed through
the hydrotime model (HT). Safflower seeds
were germinated in various polyethylene
glycol (PEG 600) solutions to obtain water
potentials of 0, -0.2, -0.4, -0.6, and -0.8
Mpa. Results indicated that germination of
safflower cultivars decreased significantly
with reduction of osmotic potential. The
highest germination percentage for Sina
(93.06 and 94.02%), Faraman (93.52 and
95.33%), Talaei (94.98 and 93.98%) and
Kouseh (93.58 and 95.55%) cultivars were
attained from distilled water (0 MPa) and
-0.2 MPa, respectively. The hydrotime
constant (θH) for Sina, Faraman, Talaei and
Kouseh cultivars were 0.93, 0.84, 0.78 and
0.72 MPa d, and the water potential (Ψb(50))
for Sina, Faraman, Talaei and Kouseh
cultivars were -0.56, -0.67, -0.64 and -0.77
MPa, respectively. Cumulative germination
of safflower seed was higher in Kouseh
cultivar, than in Sina, Faraman and Talaei
cultivars. Results showed that, hydrotime
model is suited to predicting seed
germination of safflower seeds. In addition,
the information gathered with this work
allows us to build mathematical models to
predict germination of safflower cultivars in
the field under various environments.
